Fig. 4

a Representative ambient photographs showing the effects of Ln-doped QDs on a migration of neuroblastoma cells. Photographs illustrate artificial wound at the experimental start-point (0 h) and migration of the cells after 12 h. Scale bar, 400 μm. b Bar graph demonstrating percentual migration rates. The values are expressed as the mean of six independent replicates (n = 6). Vertical bars indicate standard error. *p < 0.05, **p < 0.01 related to control non-treated cells. c Living cells fluorescence microscopy illustrating ROS (CellRox, green) formation in cells exposed to Ln-doped QDs (2 μM QDs for 3 h). Nuclei were counterstained with Hoechst 33342. Scale bars, 100 μm. BF bright field image